Ma Colton arrives home from a one-week family reunion and MacGyver arrives with the Coltons’ dog, Frog. Frank and Jesse are on a big bail case and Billy is at his grandmother's. As they go inside, a young boy runs off with a box. He climbs beneath a fence and gives the box to a teenager, T.J. Mitchell, sitting on a bike nearby. Ma Colton and MacGyver chase after the boy and Frog tracks the boy as the teenager runs off. Frog corners the thief, Ricky, and the boy explains that he had to steal the box of Frank's baseball cards or T.J. would have beaten him up. Somebody traded Ricky bogus baseball cards that they got from T.J. and Ricky tried to trade them back to T.J. T.J. caught him and forced him to steal Frank's cards. The boy tells them they can find T.J. at the Batter's Box Card Shop.
At the shop, Willard and his assistant are beating up Novus, and tell him that he needs to do what their boss Bill Marsh tells him to do since he owes the man gambling debts. Novus fights back but is quickly subdued, and Willard tells him to get the Reggie Jackson collection and tell his daughter Wendy to stop hassling their card dealers.
Ma Colton asks MacGyver to get Frank's baseball cards back, insisting the police will take their time investigating. She says she'll be down at the card shop shortly after she talks with Ricky's mother. At the baseball shop, T.J.'s buyer Eli collects the cards and leaves just as MacGyver arrives. MacGyver talks to the clerk, Tim, who is less than helpful. Wendy is in the room and tells MacGyver that T.J. made a trade with Eli and they both just left. The clerk orders her out but Wendy explains that he's selling counterfeit memorabilia. When the clerk tries to throw herout, MacGyver stops him and he throws both of them out. Wendy is eager to get MacGyver working with her and Ma Colton arrives with the list of stolen cards. Wendy notes they're worth $50,000 and Ma Colton insists that MacGyver work with Wendy despite his misgivings.
Wendy takes MacGyver to her shop, the Chalk Talk. The clerk watches them go and then calls Marsh, who is working at his printing company making counterfeit cards. Eli arrives with Frank's cards and boasts he can make perfect counterparts from them.
At her store, Wendy explains the entire memorabilia sales racket and how Bill Marsh is a major dealer. Novus comes in and tells her to drop it, but Wendy says she won't get out of it until her father does. MacGyver convinces Novus he knows baseball but Novus still orders Wendy to stay out of it before leaving. Wendy explains that Novus started gambling and ended up in debt to Marsh. Marsh has threatened to turn Novus' markers over to the gaming commission if he doesn't lend his name to Marsh's card show operations. MacGyver looks at her memorabilia, including one counterfeit item, a Walter Johnson baseball. Wendy figures they can put a tracking device in the counterfeit, sell it on the bulletin boards, and track it to Marsh's printing plant.
Marsh warns Willard that Wendy is after them, and Willard warns that Novus won't turn over the Jackson collection. His boss tells him to kill Novus if he doesn't come through.
Ma Colton makes sure that Ricky pays for stealing by reading a book for every card that he stole. MacGyver and Wendy show up and explain they're going to trade the counterfeit baseball for Ma Colton’s cards, but figure they'll end up with counterfeit cards. Ma uses her computer to put the baseball up for bid.
Disguised as Dexter Fillmore, MacGyver meets with Eli and Willard to sell the baseball for the cards. They make the trade and MacGyver meets Wendy outside, and then follow Willard when he leaves.
At home, Novus watches a pre-recorded broadcast of him introducing Reggie Jackson for the American Museum of Baseball and the dedication ceremony that Saturday when Jackson donates his collection. Marsh is watching the same broadcast and calls Novus. He warns Novus that he owes him and he wants the Jackson collection in two days or he'll be dead. Willard pulls up at Marsh's estate and MacGyver and Wendy park outside. MacGyver calls Ma Colton and asks her to identify the owner. He slips over the fence but a dog comes after him. MacGyver lures it into a tool shed and locks it in and then goes toward the house. Inside, Marsh and Willard discuss how to force Novus to steal the collection. MacGyver opens a vent and listens in. Outside, Ma Colton calls Wendy and tells her it's Marsh's house, and Wendy cuts off to go inside. She hears something moving in the tool shed and opens the door, and the dog comes after her. She holds it off with a rake but Willard notices her. They capture her and figure they can use her as leverage to force Novus to steal the collection. Willard and Marsh drive away with her and MacGyver realizes they left the baseball with the tracker at the house.
MacGyver calls Novus to tell him that Marsh has abducted Wendy. Novus refuses to call in the police and asks to talk to MacGyver in private. They arrange to meet at Ma Colton's house. Once MacGyver hangs up, Marsh calls Novus from his printing plant and tells him he now has two hours to get the Jackson collection.
Ma Colton warns MacGyver that Novus won't think straight and he'll do exactly what Marsh tells him to. They don't know where the Jackson collection is but Ma Colton knows somebody who knows somebody and makes a call.
Novus goes to the stadium and gets Jackson's collection. MacGyver and Reggie arrive and Novus explains he has to turn over the collection or Marsh will kill his daughter. Novus still refuses to call the police but Reggie and MacGyver convince him to bring the authorities in. As Novus puts the collection back, MacGyver goes to call the police on a pay phone. As soon as his back is turned, Novus drives away with the collection.
Dressed as Dexter again, MacGyver grabs a portable tape recorder and returns to the Batter's Box. He talks to Tim and asks to buy some baseball cards, claiming he has a trust fund. When MacGyver challenges him to get all the cards in 60 seconds for a $1,000 bonus, Tim takes the challenge and starts typing on his computer, but can't keep up. He offers to place a call to make the order and calls Willard. MacGyver secretly records the dial tone and tells Tim he'll be back. Outside he identifies the phone number and has Ma Colton trace it.
Novus takes the collection to Marsh's printing plant and only gives Marsh one bat and a ball. He tells Marsh that he'll get the rest when Wendy is safe. Marsh threatens to cut off Wendy's hand and Novus gives in. Meanwhile, MacGyver pulls up outside and sneaks in. He signals to Novus, using one of his baseball signals from when he played. Novus leads Willard's assistant to his car and MacGyver knocks out the man. MacGyver turns on the presses to draw Willard away while Novus goes after Wendy, disarming Marsh. Marsh runs for it with Jackson's baseball while Willard foes for the gun. MacGyver slams a cabinet door into his head, knocking him out, and then goes after Marsh. Novus insists on going as well to get Jackson's ball back. MacGyver struggles with Marsh, who hits him with the baseball and drives away. MacGyver pitches the baseball to Novus, who hits it into the scoreboard sign over the gate and knocks it down on Marsh's car.
Later, Novus promises Ma Colton that Frank's cards will be safe at the Baseball Museum. Ricky comes back and Ma Colton introduces him to Novus. Novus offers to give him an autograph... for free.